Telephone-exchange system



'R. S. WILBUR TELEPHONE EXCHANGE SYSTEM Filed Sept. 18 1923 2Sheets-Sheet 1 Ra l I/Mbu/ Nov. 9, 1926. 1,606,199

. R. S. .WILBUR TELEPHONE EXCHANGE SYSTEM I Filed Sept. 18, 1925 2Sheets-Sheet 2 //7 Van for:

Ray 5. Wilbur by -M /wy Patented Nov. 9, 1926.

RAY s. WILBUB, or LYNDHUBST, NnwJEnsnY, Ass enoaro wnsrnnnmnormoCOMPANY, INCORPORATED, OF YORK, N. Y A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

' Application filed September 18,1923. SerialN-o. 663,369.

This invention relates to telephone exchange systems .and moreparticularly to-a system in which connections are established betweentelephone lines by means of auto.- matic switching apparatus.

The object of this invention is toprovide an improved impulse circuitfor set-ting the automatic selector switches in systems of thischaracter. i

The invention will be more readily understood by referring to theaccompanying drawings, Figs. 1 and 2 and the more detailed descriptionwhich follows:

In accordance with this invention a source of alternating current,preferably within the voice range, i's provided at the central office,which upon the initiation of a call on anytelephone line is connected ina circuit including the impulse dial at the substation; Analternating'current relay at the central office, which responds to theimpulses produced by the dial, repeats these impulses into a chrectcurrent circuit including-a direct current impulse relay which controlsthe setting of the (numerical) switches t connect with the desired line.

Fig. 1 represents the called station and the usual train of selectorswitches and a portion of a trunk circuit through which these switchesare approached. Fig. 2'16PIB- sents the remainder of this trunk circuit,a line finder connected thereto and a calling subscribers station, alsoa trunk finder, and an impulse repeater connected thereto. Thisinvention may be applied to any telephone system employing automatic ormechanical switching devices, but for purposes of explanation in thisapplication it is applied to, and described in connect-ion with, thewell known Strowger system such as is described in the patent to A. H.Blessing, No. 1,176,269, March 21, 1916. The selector switches S and SFig. 1, may be of the type of the switch shown at E and the connector Cof the type of the switch I, both shown in Fig. 2 of the Blessingpatent. The apparatus shown at B Fig. 1, is part of the repeater circuitand will be described hereinafter in greater detail. r

In general, the system functions in the following manner.

One station desiring to communicate with another removes the receiverfrom the switchhook thus causing certain circuits to function andconnect acombined repeater and se lector circuit to the calling line.The repeater circuit which is'supplied with alternating currentpreferably of a frequency and magnitude within the voice range iscapable of being associated wvith a selector switch of the well knownStrowgerv type. When the calling station dials, the repeater respondingto the impulses of alternating current produced, reproduces the train ofim pulsesito energize the selector switch causing it tostep to theproper level, trunk hunt, and connect with an idle selector switchin thesucceeding trunk group in the manner well known in the art. The repeaternow controls the operation of the succeeding selector switches of thetrain in the same manner, until the connection is extended to thedesired called line when the impulse circuit is opened and the talkingcircuit is established. lVhen the conversationv is completed and thecallingstation receiver is replaced on the switch-hook the circuit isreleased and the switches are restored to normal.

Having now outlined the system and its operation in a general manner,the method of establishing a connection between stations 200 and100,'which may be in the same or separate exchanges depending upon thecode number of the station called, will be de-' scribedin detail.

Regular call.

- When the, receiver at station 200 (Fig. 2) is removed from theswitchhook line relay 204 operates. Relay 210 then operates over acircuit including a contact of relay 2&1 and brush 208 of the linefinder switch LF. It should be understood that the brushes 205 to 208inclusive move together under control of the stepping magnet 209 in-themanner hereinafter described, and that these brushes in normal positionrest upon the normal terminals as shown in Fig. 2. It should be notedthat the conductor 251 is connected. to the front contact'of all otherline relays in the same group as the line relay 204 so that the circuitto' operate relay 210 will be closed regardless of which particular linerelay in the group is operated. It should also be noted that the backcontact of each line'relay is connected to a terminal in the arc withwhich the brush 208 is associated, Relay 210 in operating closes acircuit to operate the stepping magnet 209 by way of brush 208 and thefront contact of relay 204. The stepping magnet 209 opens its ownoperating path and releases, causing the brushes 205 to 208 inclusive ofth'eswitch LF to 10-.

' leasing during hunting untilthe brushes are centered on the terminalsof the calling line. Assuming-that the brushes 205 to 208 are nowresting upon a non-calling line, its associated line relay Will not beoperated and will supply a ground to again operate the stepping magnet209 and advance the brushes of the switch LF to the terminals of thenext line in the bank, when the stepping magnet 209 releases. Assumingthese terminals are associated with the station 200 the line relay 204which is operated will prevent ground being supplied to the brush 208,hence the relay 210 will release thus preventing the stepping magnet 209from reoperating. l telay 210, in releasing, closes a circuit by way ofbrush 207, to operate relays 203 and 241 in series, thus releasing theline relay 204 and preventing the relay 2 10 from reoperating.

\Vith the brushes 205 and 206 of the line finder switch LF resting upontheterminals associated with station 200, the line is ex tended tooperate relay 111 of the selector S under control of relays 110, 11.4,and 117, by way of leads 227 and 228. Relay 111 operates relay 112, andthe latter in turn operates relay 113 both over obvious circuits. Relay241 operated, closes a circuitto operate relay 222 under control ofrelays 223, 241, 242, and brush 218 of the trunk finder TF in its normalposition. Relay 222 operated, closes a circuit to operate the steppingmagnet 219 under control of brush 218, and relays 241 and 242. It shouldbe noted that the lead 252 connected to one of the forward contacts ofrelay 241 is strapped to one of the forward contacts of all similarrelays in the group of trunk finder circuits, so that relay 222 andstepping magnet 219 will operate whenever relay 241 or some othersimilar relay operates. It should also be noted that with relay 241operated, ground will be connected to every terminal of the areassociated with brush 218 except the terminal corresponding to the trunk227, 228 connected to line finder LF.

The stepping magnet 219 operated, opens its own operating circuit andreleases, thus advancing the brushes 211 to 218 inclusive of the trunkfinder switch TF from the normal position to the terminals associatedwith the first line finder in the group.

Since this is not the line finder circuit sought, ground will beconnected to brush 21.8 by Way of the relays in the first line findercircuit corresponding to relays 241 and 242, hence the stepping magnet2.19 will reoperate and upon releasing advance the brushes 21 1 to 218inclusive of the trunl;

which terminal is free from ground, relay 222 will release thus closinga circuit controlled by relays 222 and 241 by way ol? brush 217 tooperate relays and 242 in series. The operation of'relay 242 causes theline finder circuit to test busy to all other trunk finder circuits, theoperation of relay 223 prevents relay 222 from 'reoperating, and therelease of relay 2 2 prevents the stepping magnet 219 fromadvancing thebrushes oifthe terminals associated with the line finder circuit LF. The operation of relay 223 operates relay 233 over an obvious circuit andcloses parallel circuits to operate relays 114 and 117 of the repeater R(Fig. 1), by Way of lead 226 and brush 214. Re lay 233 operatedpoperatesrelay 232 over an obvious circuit, and relay 114 prepares the impulsecircuit under control of armature 125 of relay 115 thus preventing relay111 from releasing when relay 117 operates'and prepares the operatingcircuit for relay 23 3 hereinafter described. I ,Relay 233 op'erated,closes a circuit to the source of alternating current supply 234 operaterelay 236 as follows: 234, 216, 119, 120, 121, 227, 205, 202, 201, 200,12, 206, 228, 122, 123, 124., 230, 215, 230 to ground. 'Relay 117operated closes a circuit to ground to operate relay 116 under controlof relay 241, by way of lead 225; Relay 116 operated locks to groundunder control of relay 241.

The circuit is now. ready to receive the first series ofimpulsesproduced by the substation dial'201. The dial201 is now operatedand released and as it returns to normal the loop of station 200 ismomentarily opened by the impulse contacts (not shown) of the dial 201.Relay 236 which 1s a very fast alternating current relay releases andcloses its contacts 235, thereby completing the circuit to operate relay237 under control of relays 232 and 223,' and a parallel circuit tooperate relay 115 by way ofl-eads 126 and 229 and brush 213, also undercontrol of relays 232 and 223.

Relay 237 closes an obvious circuit to operate the stepping magnet'221of the trunk finder T1 sequenceswitch which includes brushes 243 and220, whilerelay 115 being operated opens the holding circuit of theimpulse relay 111 which closes the usual circuit (not shown) to causethe selector to step in the usual manner, well known in the 111. Eachtime relay 236 releases, relay 115 operates and relay 111 releases, thusrepeating the impulse from the dial circuit to the impulse relay 111 ofthe selector S. When the impulses corresponding to the first digit ceaserelays 115 and 237 both release, the former thus holding impulse relay111 operated I as before, While the latter releases stepping magnet 221thus advancing the brushes 238 and 243 to the next terminal in theirrespective arcs. At the end of the train of impulses, the selector Shunts in a manner particularly shown and described in said patent, andselects an idle selector which we will assume to be the selector S Relay110 now operates, releasing relays 111 and 112 and extending the impulsepath controlled by relay 115 by way o f brushes 109 and the terminals108 to the impulse relay (not shown) of the selector S and the holdingground previously supplied by relay 112 to operaterelay 113, is replacedby a ground connected to lead 127 in the man ner shown in said patent.The dial 201 is again operated and released for the next digit andrelays 236., 115 and 237, and stepping magnet 221, function aspreviously described. Relay 115 now controls the circuit of theimpulserelay (not shown) of the selector S causing the selector S tofunction in a similar manner to the selector S.

At the end of this train of impulses relays 236, 237, and 115, steppingmagnet 221, and brush 220, function in the same manner as at the end ofthe first impulse train, and we will assume that the impulse circuit isextended to the connector C by way ofthe brushes 107 and terminals 106,in which case relays 104: and 105 will operate, and the final impulsingcircuit to relay 10 1 is now established under control of relay 115. Theholding ground is now supplied from the connector relay 105 in themanner shown in said patent. v

When the third digit is dialed at station 200, relay 237 operates thestepping magnet 221 which upon releasing steps the brush 220 to the nextterminal of the are 238, and after the final digit is dialed the brush220 comes to rest upon the terminal 239 of arc 238.1 During theseoperations anduntil disconnection takes place the ground to keep relay113 operated is supplied by relay 105.

\Ve will assume that't'he brushes 102 finally come 'to rest upon the"terminals 1010f the called line 100, that relay 103 operates, thecalled line is signalled, and the party answersby removing the receiverfrom the switchhookQall of which is shown and de scribed in' detail insaid patent.

When the brush 220 of the stepping mag net 221 comes torest upon theterminal 239 of are 238, an obvious circuit to operate the steppingmagnet 219 is closed by way of brush 212 and lead 246, and'the brushes211 to 218 inclusive are restored to the normal position of the trunkfinder switch 'LF. hen brush 217 steps off terminal 247 the I circuitthrough relays 242 and 223 is opened, releasing these 'relays. Relay 223released, releases relays 115, 2 33 and 237. Relay 233 releasesrelays'232 and 236. When brush 21 1 steps off terminal 248, the circuitthrough relays 114: and 117 isopened, releasing these relays andestablishing the trans mission circuit, by extending leads 227 and 228through to the brushes 102 of the con- I nector C, thence to the calledstation 100. ith the trunk finder switch TF in its normal position acircuit is closed to operate the stepping magnet 221 by Way of brushes243 and 211 to ground on the terminal 24 1. I thus restoring this switchto normal.

Disconnection.

\Vhen the conversation is completed the receiver is replaced on theswitchhook of station 200 thus releasing relay 104, which 9 in turnreleases relay 105. Relay 105 released removes, the holding circuit forcut oil relay 103, and the holding relays of the switches, and releasesrelays and 113. Relay 113 closes a circuit to operate the 105 step-pingmagnet 209 of theline finder switch LF under control of relays 114 and116 by way of lead'224.

Stepping magnet, 209 operated, opens its own operating circuit andreleases, thus step- 110 ping thebrushes-205 to 208 of the switch LFfrom the terminals associated with the line 200. When the brush 207steps 01]. the terminal 24:9, cut'ofi' relay 203 and relay 241 re lease,the former thus restoring line 200 to normal, and the latter closing acircuit to operate relay 210 by way of brush 208 and the terminal 250which will be grounded under control of the line relay (not shown)associated with the line connected to terminal 250. The stepping magnet209 'reoperates and releases thus stepping the brushes 205 to 208 of theswitch LF to the terminals of the next line otthe group. This cycle ofoperations continues until brushes 205 to 208 either find anothercalling line, in which case the new call is established in the mannerhereinbefore described, or the switch returns to normal, thati's, thebrushes of the line finder LF may be constructed as shown 130 Gallabandoned before calling Zine is found.

Should the receiver at the station 200 be removed from the switchhooklong enough for the stepping magnet 209 to operate once, the brushes 205to 208 inclusive of the switch 'LF will step to the terminals of thefirst line of the group. The release of relay 204 will cause the line200 to test busy, and relay 210 will remain operated, and the steppingmagnet 209 will step until the brushes 205 to 208 of the switch LFreturn to normal.

Gall abandoned before a repeater circa .525 found.

WVhen the receiver at station 200 is removed from the switchhook thestepping magnet 209 will step the brushes 205 to 208 inclusive to theterminals of the calling line, and relays 111 and 241 will operate inthe manner previously described under Regular call. The stepping magnet219 of the switch TF also will function, and relays 242 and 223willoperate in the manner previously described. When the call is abandoned,relay 111 of the selector S will release, releasing relay 112, whichwill release relay 113. A circuit is now closed'to operate the steppingmagnet 209 of the switch LF under control of relays 113 and 242, by wayof leads 118 and 245. The-stepping magnet 209 restores the line finderswitch LF to normal in the manner previously described underDisconnection. Relay 222 reoperates wheni'elays 223 and 241 release, andthe circuit to operate the stepping magnet 219 and restore the trunkfinder switch TF to normal is closed by way of brush 218.

Gall abandoned before dialin is commenced.

If the call is abandoned after the repeater circuit is found but beforedialing, the line finder and trunk finder switches are restored tonormal in the manner described in the last paragraph.

Gall abandoned daring dialing.

,by way of lead 224, thus releasing relays 241 and 203 and restoring theline finder switch operate the stepping magnet 219 and re store thetrunk finder switch TF to normal under control of relays 222, 241 and242 by way of brush CaZZ abandoned after dialing is completed.

The circuit is restored to normal in the manner previously describedunder Regw lar call.

lVhat is claimed is: p r

1. Atelephone system comprising a calling line equipped with a callingdevice, a called line, automatic switching apparatus at an intermediatepoint for interconnecting the calling and called lines, an alternatingcurrent source at an intermediate point, repeating means controlledby'impulses produced by interruptions oi current from said source bysaid calling device for transmitting for each alternating currentimpulse received by said repeating means a'direct current impulse andmeans for 'settingsaid automatic switching apparatus under control ofsaid direct currentimpulses. V

2. A telephone system comprising a calling line equipped with a callingdevice, a called line, automatic switching apparatus at an intermediatepoint for interconnecting the calling and called lines, an alternatingcurrent source at an intermediate. point, means for connecting saidsource to the calling line operated'when the calling line is taken foruse, repeating means controlledby impulses produced by interruptions ofcurrent from said source by said calling device for transmitting foreach alternating current impulse received by said repeating means adirect current impulse and means "for setting said automatic switchingapparatus under control of said direct current impulses.

8. A telephone system comprising a calling line equipped with a callingdevice, it called line, automatic switching apparatus at an intermediatepoint for interconnect-- ingv the calling and called line, a highfrequency alternating current source at an in termediate point,repeating means controlled by impulses produced by interruptions ofcurrent from said source by said calling device for transmitting foreach alternating current impulse received by said repeating means adirect current impulse and means for setting said automatic switchapparatus under control of said direct current impulses.

4. In a telephone system, acentral oilice,

telephone lines terminating thereat, calling dials at the stations ofsaid lines, selectors, non-numerical switches for extending callinglines to said selectors, a trunk finder,

means actuated upon the initiation of a call for setting the finder inmotion to connect with a selector taken for use by a calling line, asource of alternating current and an alternating current impulse relayassociated with said trunk finder, an impulse circuit for said relayincluding said source, said trunk finder, said non-numerical switch andthe calling line including the dial, and a second impulse circuit forcontrolling said selectors and including a source of direct current anda direct current impulse relay said secondcircuit being directlycontrolled by the alternating current relay so that for each alternatingcurrent impulse as it is received a corresponding direct current impulseis produced for the corresponding operation of said direct currentrelay.

5. In a telephone system, a central olfice, telephone lines terminatingthereat,- calling dials at the stations of said lines, selectors andconnectors, non-numerical switches for extending calling lines to saidselectors, a trunk finder, means actuated upon the initiation of a callfor setting the finder in mo tion to connect with a selector taken foruse by a-calling line, a source of alternating current and analternating current impulse relay associated with said trunk finder, animpulse circuit for said relay including said source, said trunk finder,said non-numerical switch and the calling line including its dial, asecond impulse circuit for controlling said selectors and connector andincluding a source of directcurrent and a direct current lmpulse relay,said second circuit being directly controlled by the alternating currentrelay so that for each alternating current impulse received acorresponding direct current impulse is produced for the correspo-ndingportion of said current relay and means for restoring said trunk finderupon the selection of the'called line, whereby it reverts to common use.

6. In a telephone system, a central oifice, a telephone line, a selectorat the central oflice for association with said line, a source of highfrequency current and an alternating current relay at said centraloffice, an interrupter in said telephone line, an impulse circuitincluding said source, said relay, said interrupter and the conductorsof said line, a second circuit into which impulses are repeated by saidalternating current relay and including a source of direct current, animpulse relay for setting said selector and a contact of saidalternating current relay and a switching means for disconnecting saidsources of high frequency current and alternating current responsive tothe reception of a certain number of series of impulses and meansoperative in response to such disconnection for connecting the selectorwith said conductors.

In witness whereof, I hereunto subscribe my name this 4th day ofSeptember A. D., p

RAY S. WILBUR.

